/**
*Created with IntelliJ IDEA.
*Description:
*User: 86186
*Date: 2023-09-05
*Time: 18:58
*/public class Main {
    public static void main(String[] args) {
        Test test = new Test();
        int[] arr = {1,3,2,3,1};
        int ret = test.reversePairs(arr);
        System.out.println(ret);
    }
}